DESCRIPTION (prepared by applicant): Candidate's Plans/Training: The patient-oriented research in sleep medicine and epidemiology. Training will include closely mentored completion of the research protocol, advanced epidemiological course work in patient-oriented research advanced training in sleep medicine and respiratory neurobiology . Environment: The University of Pennsylvania is a uniquely suited environment for this training award. The Center for Sleep and Respiratory Neurobiology will provide a mentored experience in patient-oriented research. The Center for Clinical Epidemiology and Biostatistics will provide advanced didactic training. Research: During pregnancy, physiologic changes including gestational weight gain take place that may place women at increased risk for the development of sleep-disordered breathing (SDB). Snoring, which is a common symptom of SDB, is a frequent complaint among pregnant women, experienced on a habitual b y as many as 23 percent of women by the end of the final trimester of pregnancy. The possibility regnant women snorers may manifest sleep-disordered breathing has remained largely unexplored. In general population, baseline obesity and weight gain are both associated with an increased risk for sleep-disordered breathing. It is our central hypothesis that pregnancy is a time of accelerated development of sleep disordered breathing in women, in which the degree of increase is likely to be larger in women with elevated baseline body mass index (BMI) or greater gestational weight gain. This protocol examines whether the number of sleep-disordered breathing events increases in women over the course of pregnancy and how baseline weight status and weight gain during pregnancy impact the degree of SDB. The specific aims of the study proposal are: 1) to test the hypothesis that the respiratory disturbance index (RDI), a measure of the number of abnormal respiratory events hourly during sleep, increases over the course of pregnancy; and to determine whether the degree of increase is greater in obese women; and 2) to identify specific clinical characteristics that influence the risk for clinically significant increases in the severity of SDB.